1. Field of the Invention
The present invention relates to a zoom lens, and an image pickup apparatus using the zoom lens, and particularly to a zoom lens which is suitable for a compact digital camera.
2. Description of the Related Art
In recent years, digital cameras in which, an arrangement has been made such that, an object is photographed by using a solid image pickup element such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) have been main stream, replacing a silver-salt film camera. Furthermore, such digital cameras have been used in a wide range of categories from a high-functional type for professional use to a portable popular type.
A user of such digital camera of the popular type seeks to enjoy photography by capturing readily various scenes at anytime and anywhere. Therefore, a small-size product, particularly a slim digital camera, which can be accommodated easily in a pocket of clothes or a bag and carried conveniently, has been preferred. Therefore, further small-sizing of a taking lens system has been sought.
Furthermore, in order that capturing can be carried out also with high intensity, a digital camera which carries out image processing such as widening sensitivity area of dynamic range has been proposed, and photography in which, capture conditions are not to be selected has become possible.
In such photography including photography at dark places, electronic correction of intensity is possible to certain extent, and furthermore, by adopting a lens with a large lens aperture, it is possible to deal with photography even at darker places, and it is possible to widen conditions under which, the photography is possible.
In a fast lens with even larger aperture, photography with clarity is possible even with a small quantity of incident light. Therefore, since a large number of options are made available to a photographer such as increasing a shutter speed in continuous capturing of a moving object, to even higher speed, in recent years, a lens with a large lens aperture has been drawing attention.
Moreover, from a point of view of widening of a capture area, the demand for high magnification zoom is still there, and even higher magnification is anticipated.
As a prior art in which, a zoom lens with a comparatively higher zoom ratio and large aperture is formed, a zoom lens which includes in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power, has been disclosed in Japanese Patent Application Laid-open Publication No. 2010-217478.